Description

Use the coordinate (coord.x, coord.y, coord.z) to do an element lookup in the 3D image object specified by image. coord.w is ignored.

read_imageh returns half floating-point values in the range [0.0... 1.0] for image objects created with image_channel_data_type set to one of the predefined packed formats or CL_UNORM_INT8 or CL_UNORM_INT16.

read_imageh returns half floating-point values in the range [-1.0... 1.0] for image objects created with image_channel_data_type set to CL_SNORM_INT8, or CL_SNORM_INT16.

read_imageh returns half floating-point values for image objects created with image_channel_data_type set to CL_HALF_FLOAT.

The read_imageh calls that take integer coordinates must use a sampler with filter mode set to CLK_FILTER_NEAREST, normalized coordinates set to CLK_NORMALIZED_COORDS_FALSE and addressing mode set to CLK_ADDRESS_CLAMP_TO_EDGE, CLK_ADDRESS_CLAMP or CLK_ADDRESS_NONE; otherwise the values returned are undefined.

Values returned by read_imageh for image objects with image_channel_data_type values not specified in the description above are undefined.